This application requests support to continue the Host-Microbe Interactions predoctoral training program that is the centerpiece of the acclaimed Microbiology and Molecular Pathogenesis Program (M2P2) at Dartmouth. M2P2 is an interdisciplinary program that includes faculty investigators from 4 departments in the Geisel School of Medicine at Dartmouth and Dartmouth College. The training program seeks to provide research and curricular-based training to a pool of talented and highly motivated students that have been recruited into our trainers' labs. The contribution of M2P2 to the Dartmouth biomedical research community has been overarching and significant as is reflected in the final report of a 2010 external review of the larger graduate program. The reviewers commented that the initiative and success of the M2P2 faculty is noteworthy, having made substantial contributions, particularly in the areas of curriculum development, student recruitment, and institutional outreach that benefited the entire program. M2P2 consists of 20 well-funded trainers ($15.6M direct costs in 2013) who collectively currently have 60 trainees in their labs. We request to continue the present level of support of 5 trainees per year. Training includes molecular, microbial, animal, human, and bioinformatics systems, which provides our trainees with a wide breadth of research and enrichment opportunities. Particular areas of strength include molecular genetics of bacterial, fungal, parasitic, and viral pathogenesis, B cell activation and interaction with T helper cells, regulation of T cell activity, mucosal immune responses, signaling events in host-pathogen interactions, viral-host interactions during sustained infection, cystic fibrosis, and applications to therapeutic and vaccine design. These areas are pursued using the full range of modern genetic, molecular, biochemical, immunologic, and bioinformatics techniques. This work is conducted in outstanding state-of-the art facilities with resources housed in modern space in a pleasant working environment. Dartmouth has invested and continues to invest heavily in its biomedical sciences infrastructure with $195M of new construction and $36M of renovations completed during the previous funding period of this training program. An additional $115M of new construction began in 2013. Students to be trained in this program are selected from the Molecular and Cellular Biology (MCB) multidisciplinary graduate program, which is the largest graduate program at Dartmouth. Students are nurtured in this highly interactive environment in which all trainees enroll in a core course, several courses in ethics, and several advanced courses and career development workshops pertinent to their area of research training. In addition they participate in weekly seminar series and journal clubs, and present their work at joint lab meetings and retreats, and an annual MCB-wide Research in Progress (RIP) presentation. Our trainees supported specifically by the T32 are also provided with a series of additional enrichment activities described in Research Training Program Plan section 2.3E.